1. Field of the Invention
This invention relates to additive modifiers for synthetic polymers or polymer blends that protect such materials against the effects of photooxidative and/or thermooxidative degradation and, in some instances, provide flame retardant properties to the synthetic polymers with which they are blended. The term "stabilizer" as used herein generally includes the various antioxidizing, heat stabilizing, light stabilizing, flame retarding, and metal deactivating properties of compounds with which the term is used. The novel stabilizers of the invention are based on the products of the reaction of hydrazido-substituted or certain amino-substituted stabilizer species with cyclic dianhydrides.
2. Description of the Prior Art
It is well known that organic polymeric materials are subject to degradation by the chemical action of light, heat and oxygen. This degradation is manifested by color development and loss of physical properties. To overcome these problems, polymers are normally protected by the incorporation of many types of thermal stabilizers, photostabilizers and antioxidant compounds.
Some stabilizer additives prepared from pyromellitic dianhydride are known. U.S. Pat. No. 4,116,930 describes the preparation of pyromellitic diimide derivatives of 3,5-dialkyl-4-hydroxyphenyl substituted amines. The compounds are used as antioxidant stabilizers for a variety of organic polymeric substances.
U.S. Pat. No. 3,821,162 discloses that certain diimide antioxidant stabilizers have also been prepared from benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride and 3,5-dialkyl-4-hydroxyphenyl substituted amines.
U.S. Pat. No. 3,904,581 discloses the pyromellitic diimide derivative of 4-amino-2,2,6,6-tetramethylpiperidine. This is an example of a hindered amine light stabilizer (HALS) diimide, useful for protecting polymeric substances from photochemical degradation.
U.S. Pat. No. 4,594,375 teaches the use of pyromellitic diimide aryl sulfonate salts as flame retardants for aromatic thermoplastic polycarbonates.
U.S. Pat. No. 4,506,047 discloses the products of the reaction of pyromellitic dianhydride with alkyl amines forming bis-pyromellitic derivatives that, when added to polycarbonate resins, provide compositions with improved physical properties.
As disclosed in U.S. Pat. No. 3,661,912, certain hydrazides have been reacted with 3,4,9,10-perylene-tetracarboxylic dianhydride for use as non-fading dye compositions. However these compositions were not stabilizer additives for polymers.
U.S. Pat. No. 4,212,880 discloses acyl amino-substituted pyromellitic diimides as feed additives for agricultural applications. Use of these derivatives was not contemplated for the stabilization of organic polymeric materials. None of the compounds prepared contained recognizable photostabilizers or thermal stabilizer groups.
U.S. Pat. No. 3,956,331 describes the reaction of salicyloyl hydrazine with many anhydride compounds including pyromellitic dianhydride to produce N-(salicyloylamino)imides. These imide materials are claimed to be stabilizers for polyolefin compositions. A related patent, U.S. Pat. No. 3,933,736, claims these stabilized polyolefin compositions to be resistant to the degradative effects of heavy metals, such as copper.
U.S. Pat. No. 4,581,396 describes the use of pyromellitic diimides as fire retardants for polymers. The additive was prepared by reacting pyromellitic dianhydride with pentabromobenzylamine.